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The photochemical generation of nicotinamide cofactor 1,4-NADH, facilitated by inorganic photosensitizers, emerges as a promising model system for investigating charge transfer phenomena at the interface of semiconductors and bacteria, with implications for enhancing photosynthetic biohybrid systems (PBSs). However, extant semiconductor nanocrystal model systems suffer from achieving optimal conversion efficiency under visible light. This study investigates quasi-one-dimensional CdS nanorods as superior light absorbers, surface modified with catalyst Cp*Rh(4,4′-COOH-bpy)Cl2 to produce enzymatically active NADH. This model subsystem facilitates easy product isolation and achieves a turnover frequency (TOF) of 175 h–1, one of the highest efficiencies reported for inorganic photosensitizer-based nicotinamide cofactor generation. Charge transfer kinetics, fundamental for catalytic solar energy conversion, range from 106 to 108 s–1 for this system highlighting the superior electron transfer capabilities of NRs. This model ensures efficient cofactor production and offers critical insights into advancing systems that mimic natural photosynthesis for sustainable solar-to-chemical synthesis. 

A bias-free photochemical diode, in which a p-type photocathode is connected to an n-type photoanode to harness light for driving photoelectrochemical reduction and oxidation pairs, serves as a platform for realizing light-driven fuel generation from CO2. However, the conventional design, in which cathodic CO2 reduction is coupled with the anodic oxygen evolution reaction (OER), requires substantial energy input. Here we present a photochemical diode device that harnesses red light (740 nm) to simultaneously drive biophotocathodic CO2-to-multicarbon conversion and photoanodic glycerol oxidation as an alternative to the OER to overcome the above thermodynamic limitation. The device consists of an efficient CO2-fixing microorganism, Sporomusa ovata, interfaced with a silicon nanowire photocathode and a Pt–Au-loaded silicon nanowire photoanode. This photochemical diode operates bias-free under low-intensity (20 mW cm−2) red light irradiation with ~80% Faradaic efficiency for both the cathodic and anodic products. This work provides an alternative photosynthetic route to mitigate excessive CO2 emissions and efficiently generate value-added chemicals from CO2 and glycerol 

Photocathodic conversion of NAD+ to NADH cofactor is a promising platform for activating redox biological catalysts and enzymatic synthesis using renewable solar energy. However, many photocathodes suffer from low photovoltage, consequently requiring a high cathodic bias for NADH production. Here, we report an n+p-type silicon nanowire (n+p-SiNW) photocathode having a photovoltage of 435 mV to drive energy-efficient NADH production. The enhanced band bending at the n+/p interface accounts for the high photovoltage, which conduces to a benchmark onset potential [0.393 V vs the reversible hydrogen electrode (VRHE)] for SiNW-based photocathodic NADH generation. In addition, the n+p-SiNW nanomaterial exhibits a Faradaic efficiency of 84.7% and a conversion rate of 1.63 μmol h–1 cm–1 at 0.2 VRHE, which is the lowest cathodic potential to achieve the maximum productivity among SiNW-sensitized cofactor production.